Jolokia1.2.3

New year, new release. Ok, it's not the BIG 2.0 which I already somewhat promised. Anyways, another big feature jumped on the 1.x train in the last minute. It is now possible to find agents in your network by sending an UDP packet to the multicast group 239.192.48.84, port 24884. Agents having this discovery mechanism enabled will respond with their meta data including the access URL. This is especially useful for clients who want to provide access to agents without much configuration. I.e. the excellent hawt.io will probably use it one way or the other. In fact, it was hawt.io which put me on track for this nice little feature ;-)

Discovery is enabled by default for the JVM agent, but not for the WAR agent. It can be easily enabled for the WAR agent by using servlet init parameters, system properties or environment variables. All the nifty details can be found in the reference manual.

Jolokia is an open source, completely free and easy-to-use software implemented in Java and designed from the offset to be used for accessing JMX with JSON over HTTP remotely. It's more like JMX on Capsaicin. It doesn't have a graphical user interface (GUI).

As a matter of fact, Jolokia is a JMX-HTTP bridge providing an alternative to JSR-160 connectors. It is simple, fast, polyglot, secure, firewall-friendly and includes various unique features like bulk-requests.

Features at a glance

Key features include support for processing as many JMX (Java Management Extensions) requests as possible in just one network roundtrip and support for wrapping multiple Jolokia requests in a JSON (JavaScript Object Notation) payload.

Support for running in agentless mode, JSON/HTTP proxy support for Jolokia requests, support for sending bulk requests into multiple JSR-160 requests, support for custom policies that include fine grained restrictions, as well as support for wildcards and allow/deny sections in custom policies.

In addition, the application supports parsing of requests and building of responses by using the json-simple JSON serialization library software, and support for balancing multiple use cases with state-of-the-art features, such as low startup times and bulk requests.

Jolokia is an easy to install software that can only be accessed via a supported web browser. It can be accessed on any platform by using a configurable, REST-like URL encoding feature. The software runs on multiple HTTP proxy hops.

Under the hood and supported OSes

Taking a look under the hood of Jolokia, we can notice that the Java programming language has been used to write the program, which means that it is platform-independent, supported on GNU/Linux, Mac OS X and Microsoft Windows operating systems.

For your convenience, it is available for download as both pre-built binaries and a source tarball. It has been successfully tested on both 32-bit and 64-bit computers.

Jolokia was reviewed by Marius Nestor, last updated on December 2nd, 2014